"I don't see the lines getting any shorter," Founding Director Lonnie Bunch said in an interview, days before the museum marked its six-month anniversary. "I don't think we're going to have those moments when I can bounce a basketball through the museum - at least not for the next three or four or five years."

Interest in the long-awaited museum, which was designed by the firm led by Durham architect Phil Freelon, shows no sign of decline. In its first six months, the $540 million, 400,000-square-foot structure on the Mall has welcomed 1,211,563 visitors, placing it among the four most-popular Smithsonian museums. Attendance is well short of pre-opening predictions of 3 million to 3.5 million visitors a year, but the peak seasons of spring break and summer are still ahead.

And that means crowds will grow, Bunch said.

Part of the challenge with a new building is you have to figure out how it works."

Lonnie Bunch

"Part of the challenge with a new building is you have to figure out how it works," he said. Officials projected guests would spend three hours — twice as long as a typical Smithsonian visit — but they are staying up to six hours.

The museum's design has also caused choke-points. For example, the intentionally cramped entrance to the slavery section on the lowest level can't handle the number of people who can fit into the massive elevator that ferries guests below ground. Museum officials have decided to not fill the elevator to capacity, which causes lines at the elevator two levels above.

Bunch says they predicted visitors getting off the elevator would move more briskly through the area or push beyond the crowds. "But here, people are stopping and reading," he said.

They have decided to have visitors wait to get into the space rather than have it become so crowded that it becomes an unpleasant experience. "There's not much bitching," Bunch said. "There's a sense of 'I really want to see it.' "

Museum council member Patty Stonesifer said access remains the leadership's priority. "The biggest wish we all have is that it would be easier to come and go (without) the worries about planning ahead, and tickets and lines," she said.

Contributing to those worries are the problematic release of advance timed passes, which have caused headaches when demand overwhelms the museum's website. Bunch said he "pitched a fit" when technical problems arose again in February, after earlier troubles in the fall.

"I said, 'I'm not doing this. You know what I think about passes. Make it work,'" he recalled. But this month's release of June passes went smoothly, he said, giving him confidence that "we now have a system that will work."

Bunch said he will assess the continued use of passes after September, when the museum has been open for a year.

"Maybe we can just do passes for large groups," he said, noting that officials are looking at options. "I was never the biggest fan of timed passes, so as soon as I can figure out other alternatives, it's gone."

Bunch has received lots of opinions about the museum's inaugural exhibitions, especially from visitors who feel slighted. They ask for more focus on scientists, more black architects, more black cardiologists, he said. In addition, the museum has received a petition with 15,000 signatures seeking a spotlight for Clarence Thomas, who is mentioned in the context of his controversial nomination hearings.

Although he welcomes the feedback, Bunch bristles at the suggestion that the museum has a political bent. "You could make an argument that we should have done more on the Supreme Court. We decided not to," he said. "But there was never any decision not to tell stories about a particular individual because of their politics. Otherwise, why is Ben Carson here?"

Carson joined President Donald Trump for an early-morning tour last month that included discussions about early presidents, and about the slave trade being the first international business.

"Anytime you have a new president, you want this person to care about the Smithsonian," Bunch said about the visit.

"There was a lot that was new to him, and I'm not going to argue that he suddenly thought about Jefferson in new ways or Muhammad Ali," he said. "But I think he realized these were important stories. I was pleased when he said he'd come back. I take him at his word. And the fact that he tweeted that it was amazing? I'm a happy guy."

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